“…This process typically induces increased surface roughness, strain hardening and compressive residual stresses (CRS) within the surface layer [4]. Many investigations have focused on the effect of shot peening on fatigue behaviour in different material systems such as steel [1,3,[5][6][7], aluminium [8][9][10][11][12][13], titanium [8], magnesium [8,14,15] alloys and nickel-based superalloys [16,17]. It can be generally concluded that the roughened surface after the peening treatment may accelerate crack initiation [8], on the other hand, the CRS and strain hardening effects can compensate for this by deferring the short crack onset and propagation process [5,9,10,14,18].…”